Description
Red-tailed Black Cockatoos are around 60 centimetres (24 in) in length and sexually dimorphic. The male's plumage is all black with a prominent black crest made up of elongated feathers from the forehead and crown. The bill is dark grey. The tail is also black with two lateral bright red panels. Females are black with yellow-orange stripes in the tail and chest, and yellow grading to red spots on the cheeks and wings. The bill is pale and horn-coloured. The underparts are barred with fine yellow over a black base. Male birds weigh between 670 and 920 grams (1.5–2 lb), while females weigh slightly less at 615–870 grams (1.25–1.75 lb). In common with other cockatoos and parrots, Red-Tailed Black Cockatoos have zygodactyl feet, two toes facing forward and two backward, that allow them to grasp objects with one foot while standing on the other, for feeding and manipulation. Black cockatoos are almost exclusively left-footed (along with nearly all other cockatoos and most parrots).
Juvenile Red-tailed Black Cockatoos resemble females until puberty, which occurs around four years of age, but have paler yellow barred underparts. As the birds reach maturity, males gradually replace their yellow tail feathers with red ones; the complete process takes around four years.
As with other cockatoos, the Red-tailed Black Cockatoo can be very long-lived in captivity; in 1938, ornithologist Neville Cayley reported one over fifty years old at Taronga Zoo. Another bird residing at London and Rotterdam Zoos was 45 years and 5 months of age when it died in 1979.
Several calls of Red-tailed Black Cockatoos have been recorded. The bird's contact call is a rolling metallic krur-rr or kree, which may carry long distances and is always given while flying; its alarm call is sharp. Displaying males vocalize a sequence of soft growling followed by a repetitive kred-kred-kred-kred.
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